Catalyst manufacture



attach CATALYST 'w:

Robert E. Burk, Cleveland Heights, Ohio, asslgnor.

to The Standard Oil Company, Cleveland, Ohio, a corporation of Ohio in Drawing. Original application September 19, 1938, Serial No. 230,656. Divided and this application Qctober 25, 1941, Serial No. 416,591

8 Claims. (Cl. 252-254) In catalysts prepared by co-precipltation from dissolved salts of two or more elements, the general experience is that the activity of the catalyst is not as uniform or as well sustained as might be reasonably expected and as is desirable, and furthermore there may be considerable variation in successive batches of the same catalyst. I have found that this is a consequence of the conventional methods of manufacture. But, in accordance with the present invention, catalyst preparations may be had, which are thoroughly uniform in composition and which have activity of consistent and sustained character and a given catalyst may be reproduced without undesirable variation.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative however, of but a few of the various ways in which the principle of the invention may be employed.

If, as in accordance with the known and usual modes of procedure, a mixture such as for example the salts titanium chloride and chromium chloride or nitrate, be in solution, the solution mixture may be maintained only if the solution is rather strongly acid. On addition of a base, the titanium is first precipitated and then the chromium and the precipitate so formed found to be non-uniform, the relative amounts of titanium and of chromium varying greatly from the inside to the surface of the precipitated masses. This diflerential is found to exist in greater or less degree generally where two or more elements are co-precipitated, and even where the solubility properties of the desired various components would not indicate such effects so plainly, it is nevertheless there. Thus, when catalyst components are precipitated, the formation of respective nuclei of each is dependent upon various factors such as the speed of diffusion of ions of each, and the number of molecules of catalyst required to form a nucleus which is in turn related to such factors as surfacetension; and if a catalyst which involves oxides of two metals in definite proportions and molecularly mixed is desired, this is not obtained by gross precipitation from a solution in which the components are present in the theoretical proportions. In proceeding in accordance with my invention, only a small amount of the soluble salts in solution are present in the precipitating ions are still in the field, and with the more easily precipitated component going down at a rate greater than the less easily precipitated component their relative concentrations change in adjustment to the point representing equilibrium for the proportions desired in the precipitate, and with the further feed of the catalyst salts in their proportions and the feed of the precipitant at a rate equivalent to the oncoming catalyst salts, the desired equilibrium proportion in the precipitate is maintained. Thus, in mixing a precipitant with the dissolved salts, a particularly desirable procedure is to start the introduction of the dissolved salts into a mixing zone, and when a small'body of such liquid has accumulated the introduction of the precipitant is started, and this in-such condition occasions a beginning precipitation during which concentration adjustment of each component is attained so that on the continuing introduction of all of the reacting components in proper proportlons, the adjustment of concentrations will continue, established at an equilibrium which corresponds to the formation of a precipitate with the components in the desired proportion, uniforrnly and molecularly mixed. Otherwise, it would be necessary, where starting both .the precipitant and the salt solution feeds at the same time, to accurately control the feed of less precipitant for a while, then adjust the feed of precipitant to the in-coming feed of salt solution, a routine which while feasible is not quite so generally convenient as that first-mentioned. This procedure is outstandingly useful in producing catalysts on large scale, being convenient and also positive in uniformity of results.

As an example: Nitrates of aluminum and chromium are dissolved in distilled water at the .is started, for instance concentrated ammonium hydroxide 2310 grams and ammonium acetate 1 solution by adding alcohol.

1500 grams per 11.2 liters oi distilled water. The supplying of the components, thus with a lag of the precipitant, is continued, and with apparatus involving suitable arrangements for continuous relative feeds and passing on to suitable settling zones, a continuous type of catalyst production may be had. As reaction by the precipitant present occurs promptly, the precipitation takes place in the mixing zone, and the settling zones serve,

' pumping or how into an agitating mixing zone is started. And in sequence pumping in or flow of a precipitant, ammonium hydroxide for instance at the rate of 2310 grams concentrated ammonium hydroxide and 1500 grams of ammonium acetate per 11.2 liters of distilled water is started,

and the ultimate precipitate is separated and washed and dried as foregoing.

As another example:- Beryllium nitrate at the rate for instance of 0.01 mol, and ammonium acetate 40 grams per 1.6 liters of water, and chromium nitrate at the rate of for instance 0.2 mol in 0.7 liters of water are provided, and the mix ture is heated to ell-60 C. and flow to an agitating mixing zone is started. Then flow of a precipitant, for instance ammonium hydroxide as at the rate of 65 grams concentrated ammonium hydroxide per 0.8 liters of .water, is started. The precipitate formed by the supplying of the com ponents is separated and washed and dried.

As another example: Ethyl silicate and a solution of CI(NO3)3 are brought into homogeneous Proportions may be 4 mols SiOa to 6 of C1203. This is pumped into a reaction zone where the same volume is maintained and where NHiQH containing alcohol sufficient to prevent separation of liquid unhydrolyzed ethyl silicate is added. The NHQOH is in rate for instance of 713, 2500 and 1770 grams respectively per 18.8 liters of distilled water, being dissolved and the solution warmed to about 55 C.', pumping thereof is started into a mixing zone. Then pumping of a precipitant, ammonium hydroxide at the rate for instance of 91 grams concentrated ammonia per 2 liters of water, is started. The precipitate is separated, washed and dried.

The supplying of the liquids to the mixing zone may be by pumping or pressure or gravity flow, conveniently, and as indicated, in some instances a component may be included'in the precipitant feed. Where the components are compatible they may be brought in a stream together into the mixing zone or they can be brought in as separate streams, but where they are incompatible a' titanium and the like where precipitation would occur too quick. it is advantageous to recycle 9. rather large volume of liquid from the mixing zone back into the fresh feed stream of the components which are to be precipitated. Advantageously, in a mixing zone a constant level of body of liquid may be maintained by siphoning or overflow.

As-seen, in such co-precipltation, various components can be combined, and the proportions of the components may be as desired in any given instance, this process giving in all instances a condition of precipitation in which initially the precipitant is in slightly deficient relative supply and adjustment to equilibrium .thereon occurs, and the supply of the components is then continued, the ions being provided as required. Such catalysts as of the oxide and sulphide type, involving for instance elementsfrom the first, second, third, fourth, fifth and sixth groups of the periodic system excepting usually alkali metal, alkaline earth metals, scandium, yttrium, lanthanum, carbon, selenium, tellurium, polon-' ium, nitrogen and phosphorus, are thus prepared with particular efficacy and uniformity and stability.

This application is a division of my application Serial No. 230,656, filed September 19, 1938.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly. claim as my invention:

1. In a process for preparing gel type plural oxidecatalysts of definite composition wherein hydrous gel type plural oxides are precipitated which ingredients form said hydrous oxides upon treatment with said precipitant, the improvement which comprises maintaining flowing streams of an ingredient solution and precipitant into the mixing zone, said ingredients being so proportioned relative to one another as to produce a product of hydrous gel type plural oxides of the desired final composition if treated with sufllcient precipitant for complete precipitation, and the precipitant being introduced at a rate such that enough precipitant in any given time is introduced to completely precipitate all ingredients introduced during the same period of time, but commencing the introduction to the mixing zone of the flow of precipitant after the flow of ingredient solution has started.

2. In a process for preparing gel type plural oxide catalysts of definite composition wherein -hydrous gel type plural oxides are precipitated by means of a precipitant from a solution containing soluble ingredients in a mixing zone which ingredients form said hydrous oxides upon treatment with said precipitant, the improvement whichcomprises maintaining flowing streams of a solution of nitrates of chromium and aluminum and ammonium hydroxide solution containing tin into the mixing zone, said inassaesr for complete precipitation, and the ammonium hydroxide being introduced at a rate such that enough in any given time is introduced to completely precipitate all ingredients introduced during the same period of time, but commencing the introduction oi the ammonium hydroxide to the mixing zone after the flow of the other solu-- tion has started.

3. In a process for preparing gel type plural oxide catalysts of definite composition wherein hydrous gel type plural oxides are precipitated by means of a precipitant from a solution containing soluble ingredients in a mixing zone which ingredients form said hydrous oxides upon treatment with said precipitant, the improvement which comprises maintaining flowing streams of a solution of nitrates oi beryllium and chromium and an ammonium hydroxide solution into the mixing zone, said ingredients being so proportioned relative to one another as to yield a product oi hydrous gel type plural oxides of the desired final composition ii treated with suificient ammonium hydroxide for complete precipitation, and the ammonium hydroxide being introduced at a rate such that enough in any given time is introduced to completely precipitate all ingredients introduced during the same period of time, but commencing the introduction of the-ammonium hydroxide to the mixing zone after the fiow of the other solution has started.

4. In a process for preparing gel type plural oxide catalysts oi definite'composition wherein hydrous gel type plural oxides are precipitated by means of a precipitant from a solution containing soluble ingredients in a mixing zone which ingredients iorm said hydrous oxides upon ingredient solution has started, and maintaining a fixed level in the mixing zone and recycling liquid therefrom in addition to the fiow oi ingredient solution.

6 In a process for preparing gel type plural oxide catalysts oi definite composition wherein hydrous gel type plural oxides are precipitated by means of a precipitant from a solution containing soluble ingredients sin a mixing zone which ingredients form said hydrous oxides upon treatment with said precipitant, the improvement which comprises maintaining flowing streams of a solution of salts of at least two catalyst elements and a precipitant into the mixing zone, said ingredients being so proportioned relative to one another. as to produce a product of hydrous gel type plural oxides areprecipitated treatment with said precipitant, the improvement I which comprises, flowing streams oi arf ingredient solution and a precipitant into the mixing zone, said ingredients being proportioned relative to one another as for the desired final product it treated with sumcient precipitant ior complete precipitation, but at first the precipitant being fed insufilcient in a given period of time to precipitate out all oi the catalyst ingredients being suppliedduring said period, and then said ingredients being so proportioned relative to one another as to produce a product 01' hydrous gel t pe plural oxides oi the desired final composition and the precipitant being introduced at a rate that in any given time is suificient to completely precipitate all oi the catalyst ingredients introduced during the same period of time.

5. In a process for preparing gel type plural oxide catalysts oi definite composition wherein hydrous gel type plural oxides are precipitated by means of a precipitant irom a solution containing soluble ingredients in a mixing zone which ingredients iorm said hydrous oxides upon treatment with said precipitant, the improvement which comprises maintaining flowing streams of an ingredient solution and precipitant into the mixing zone, said ingredients being so proportioned relative to one another as to produce a product oi hydrous gel type plural oxides oi the desired final composition ii treated with sufiicient precipitant for complete precipitation, and the precipitant being introduced at a rate such that enough precipitant in any given time is introduced to completely precipitate ail ingredients introduced during the same period oi time, but commencing the introduction to the mixing zone oi the fiow oi precipitant after the flow oi introduced during the same period oi time, but

roportioned relative to one anotheras to produce a product oi hydrous gel type plural oxides oi the desired final composition ii treated with sumcient precipitant for complete precipitation, and the precipitantbeing introduced at a rate such that enough precipitant in any given time is introduced to completely precipitate all ingredients introduced during the same period of time, but commencing the introduction to the mixing zone of the fiow oi precipitant after the fiow oi ingredient solution has started, and recycling liquid from the mixing zone in addition to the ingredient solution feed stream.

8. In a process for preparing gel type Plural oxide catalysts oi definite composition wherein hydrous gel type Plural oxides are Precipitated by means oi a precipitant from a solution containing soluble ingredients in a mixing zone which ingredients iorm said hydrous oxides upon treatment with said precipitant, the improvement which comprises maintaining flowing oi an ingredient solution and precipitant into the mixing zone, said "ingredients being so proportioned relative to one another as to produce a product oi hydrous gel type plural oxides oi the desired final composition it treated with sumcient precipitant ior complete precipitation, and the precipitant being introduced at a rate such that enough precipltantin any given time is introduced to completely precipitate all ingredients commencing the introduction to the mixing zone oi the flow oi precipitant after the ilow oi ingredie'nt solution has started, and drawing 03 liquid in excess oi a fixed volume body.

/ 'rn hoax. 

